Re: [PATCH] lockd: unlock lockd locks held for a certain filesystem

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Apr 23, 2008 at 04:39:11PM -0400, Wendy Cheng wrote:
> #if defined(BRUCE_CHECK_THIS_OUT)
> error = nlmsvc_failover_path(nd.path.mnt->mnt_sb);
> #else
> error = nlmsvc_failover_path(nd.mnt->mnt_sb);
> #endif

The vfsmount and dentry got moved into the path argument sometime in the
last kernel version or so.  Is there a macro defining the latter as a
shortcut for the former?  I didn't see one.

--b.

>
> -- Wendy
>
> ---------- based on the following email ----------------------------
>
> J. Bruce Fields wrote:
>> On Wed, Apr 23, 2008 at 09:44:22AM +0200, Christoph Hellwig wrote:
>>   
>>> Please don't pass down the nameidata, but just the super_block.  That's
>>> all we need in the lower layer functions.
>>>     
>>
>> Yep, I agree that's nicer; here's the result.
>>
>> --b.
>>
>> commit 26a816586b71877d8a84fbb436373099384e328b
>> Author: Wendy Cheng <wcheng@redhat.com>
>> Date:   Thu Jan 17 11:10:12 2008 -0500
>>
>>     lockd: unlock lockd locks held for a certain filesystem
>>         Add /proc/fs/nfsd/unlock_filesystem, which allows e.g.:
>>         shell> echo /mnt/sfs1 > /proc/fs/nfsd/unlock_filesystem
>>         so that a filesystem can be unmounted before allowing a peer 
>> nfsd to
>>     take over nfs service for the filesystem.
>>         Signed-off-by: S. Wendy Cheng <wcheng@redhat.com>
>>     Cc: Lon Hohberger  <lhh@redhat.com>
>>     Cc: Christoph Hellwig <hch@lst.de>
>>     Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
>>          fs/lockd/svcsubs.c          |   66 
>> +++++++++++++++++++++++++++++++++++++++-----
>>      fs/nfsd/nfsctl.c            |   65 +++++++++++++++++++++++++++++++++++++++++++
>>      include/linux/lockd/lockd.h |    7 ++++
>>      3 files changed, 131 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
>> index e12daba..dcdcff6 100644
>> --- a/fs/lockd/svcsubs.c
>> +++ b/fs/lockd/svcsubs.c
>> @@ -196,6 +196,12 @@ again:
>>  	return 0;
>>  }
>>  +static int
>> +nlmsvc_always_match(void *dummy1, struct nlm_host *dummy2)
>> +{
>> +	return 1;
>> +}
>> +
>>  /*
>>   * Inspect a single file
>>   */
>> @@ -232,7 +238,8 @@ nlm_file_inuse(struct nlm_file *file)
>>   * Loop over all files in the file table.
>>   */
>>  static int
>> -nlm_traverse_files(void *data, nlm_host_match_fn_t match)
>> +nlm_traverse_files(void *data, nlm_host_match_fn_t match,
>> +		int (*is_failover_file)(void *data, struct nlm_file *file))
>>  {
>>  	struct hlist_node *pos, *next;
>>  	struct nlm_file	*file;
>> @@ -241,6 +248,8 @@ nlm_traverse_files(void *data, nlm_host_match_fn_t match)
>>  	mutex_lock(&nlm_file_mutex);
>>  	for (i = 0; i < FILE_NRHASH; i++) {
>>  		hlist_for_each_entry_safe(file, pos, next, &nlm_files[i], f_list) {
>> +			if (is_failover_file && !is_failover_file(data, file))
>> +				continue;
>>  			file->f_count++;
>>  			mutex_unlock(&nlm_file_mutex);
>>  @@ -345,7 +354,7 @@ void
>>  nlmsvc_mark_resources(void)
>>  {
>>  	dprintk("lockd: nlmsvc_mark_resources\n");
>> -	nlm_traverse_files(NULL, nlmsvc_mark_host);
>> +	nlm_traverse_files(NULL, nlmsvc_mark_host, NULL);
>>  }
>>   /*
>> @@ -356,7 +365,7 @@ nlmsvc_free_host_resources(struct nlm_host *host)
>>  {
>>  	dprintk("lockd: nlmsvc_free_host_resources\n");
>>  -	if (nlm_traverse_files(host, nlmsvc_same_host)) {
>> +	if (nlm_traverse_files(host, nlmsvc_same_host, NULL)) {
>>  		printk(KERN_WARNING
>>  			"lockd: couldn't remove all locks held by %s\n",
>>  			host->h_name);
>> @@ -376,8 +385,27 @@ nlmsvc_invalidate_all(void)
>>  	 * turn, which is about as inefficient as it gets.
>>  	 * Now we just do it once in nlm_traverse_files.
>>  	 */
>> -	nlm_traverse_files(NULL, nlmsvc_is_client);
>> +	nlm_traverse_files(NULL, nlmsvc_is_client, NULL);
>> +}
>> +
>> +static int
>> +nlmsvc_failover_file_ok_path(void *datap, struct nlm_file *file)
>> +{
>> +	struct super_block *sb = datap;
>> +
>> +	return sb == file->f_file->f_path.mnt->mnt_sb;
>> +}
>> +
>> +int
>> +nlmsvc_failover_path(struct super_block *sb)
>> +{
>> +	int ret;
>> +
>> +	ret = nlm_traverse_files(sb, nlmsvc_always_match,
>> +				 nlmsvc_failover_file_ok_path);
>> +	return ret ? -EIO : 0;
>>  }
>> +EXPORT_SYMBOL_GPL(nlmsvc_failover_path);
>>   static int
>>  nlmsvc_failover_file_ok_ip(void *datap, struct nlm_host *host)
>> @@ -391,7 +419,8 @@ int
>>  nlmsvc_failover_ip(__be32 server_addr)
>>  {
>>  	int ret;
>> -	ret = nlm_traverse_files(&server_addr, nlmsvc_failover_file_ok_ip);
>> +	ret = nlm_traverse_files(&server_addr, nlmsvc_failover_file_ok_ip,
>> +						NULL);
>>  	return ret ? -EIO : 0;
>>   }
>> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
>> index 02c3949..b4ca5c9 100644
>> --- a/fs/nfsd/nfsctl.c
>> +++ b/fs/nfsd/nfsctl.c
>> @@ -55,6 +55,7 @@ enum {
>>  	NFSD_List,
>>  	NFSD_Fh,
>>  	NFSD_FO_UnlockIP,
>> +	NFSD_FO_UnlockFS,
>>  	NFSD_Threads,
>>  	NFSD_Pool_Threads,
>>  	NFSD_Versions,
>> @@ -92,6 +93,7 @@ static ssize_t write_recoverydir(struct file *file, char *buf, size_t size);
>>  #endif
>>   static ssize_t failover_unlock_ip(struct file *file, char *buf, 
>> size_t size);
>> +static ssize_t failover_unlock_fs(struct file *file, char *buf, size_t size);
>>   static ssize_t (*write_op[])(struct file *, char *, size_t) = {
>>  	[NFSD_Svc] = write_svc,
>> @@ -103,6 +105,7 @@ static ssize_t (*write_op[])(struct file *, char *, size_t) = {
>>  	[NFSD_Getfs] = write_getfs,
>>  	[NFSD_Fh] = write_filehandle,
>>  	[NFSD_FO_UnlockIP] = failover_unlock_ip,
>> +	[NFSD_FO_UnlockFS] = failover_unlock_fs,
>>  	[NFSD_Threads] = write_threads,
>>  	[NFSD_Pool_Threads] = write_pool_threads,
>>  	[NFSD_Versions] = write_versions,
>> @@ -319,6 +322,33 @@ static ssize_t failover_unlock_ip(struct file *file, char *buf, size_t size)
>>  	return nlmsvc_failover_ip(server_ip);
>>  }
>>  +static ssize_t failover_unlock_fs(struct file *file, char *buf, 
>> size_t size)
>> +{
>> +	struct nameidata nd;
>> +	char *fo_path;
>> +	int error;
>> +
>> +	/* sanity check */
>> +	if (size == 0)
>> +		return -EINVAL;
>> +
>> +	if (buf[size-1] != '\n')
>> +		return -EINVAL;
>> +
>> +	fo_path = buf;
>> +	if (qword_get(&buf, fo_path, size) < 0)
>> +		return -EINVAL;
>> +
>> +	error = path_lookup(fo_path, 0, &nd);
>> +	if (error)
>> +		return error;
>> +
>> +	error = nlmsvc_failover_path(nd.path.mnt->mnt_sb);
>> +
>> +	path_put(&nd.path);
>> +	return error;
>> +}
>> +
>>  static ssize_t write_filehandle(struct file *file, char *buf, size_t size)
>>  {
>>  	/* request is:
>> @@ -729,6 +759,8 @@ static int nfsd_fill_super(struct super_block * sb, void * data, int silent)
>>  		[NFSD_List] = {"exports", &exports_operations, S_IRUGO},
>>  		[NFSD_FO_UnlockIP] = {"unlock_ip",
>>  					&transaction_ops, S_IWUSR|S_IRUSR},
>> +		[NFSD_FO_UnlockFS] = {"unlock_filesystem",
>> +					&transaction_ops, S_IWUSR|S_IRUSR},
>>  		[NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR},
>>  		[NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
>>  		[NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
>> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
>> index f06d2db..7cd9c8e 100644
>> --- a/include/linux/lockd/lockd.h
>> +++ b/include/linux/lockd/lockd.h
>> @@ -220,6 +220,7 @@ void		  nlmsvc_invalidate_all(void);
>>  /*
>>   * Cluster failover support
>>   */
>> +int           nlmsvc_failover_path(struct super_block *sb);
>>  int           nlmsvc_failover_ip(__be32 server_addr);
>>   static __inline__ struct inode *
>>   
>